1. Field of the Invention
The present invention relates generally to fabrication of electronic components and particularly to fabrication of components for disk drive heads.
2. Description of the Prior Art
Photomasking is a technique which is commonly used in making electronic components. It is especially useful in many patterned deposition processes in which layers are deposited one upon another, but there may be a need to block off certain areas from the deposition of one or more layers. This is commonly done by depositing photomask material, usually a photo-resist material, which hardens when exposed to certain wavelengths of light, to mask off certain areas. Unexposed areas of the photoresist material are then removed. After the deposition of the layer is done, the photomask is removed, or lifted off, taking the deposition material with it to leave an un-coated portion.
Conventional prior art photomask materials are useful for certain operations which can be accomplished within a range of lower temperatures. However, certain other operations which are becoming more widely used, must be conducted at higher temperatures, for which these prior art photomask materials are not suited.
One example which illustrates the limitations of prior art photomask materials can be found in the fabrication of disk drive heads. TMR (Tunnel Magnetoresistance) and other CPP (Current Perpendicular to the Plane) read head devices utilize a dielectric layer to confine electrical current to the sensor area. Since practical CPP devices in the deep submicron regime require self-aligned processing for patterning and isolation, the patterning techniques used must be compatible with the deposition techniques for each of the layers. Conventional photo processing materials poorly tolerate temperatures in excess of 130 degrees C. limiting applicable deposition techniques for the dielectric layer to those that are PVD (Physical Vapor Deposition)-based. PVD-based deposition techniques lack the conformality and low defect density of CVD (Chemical Vapor Deposition) techniques such as ALD (Atomic Layer Deposition). A complete review of ALD-based deposition techniques and their benefits is described by Ritala and Leskelä in Handbook of Thin Film Materials, H. S. Nalwa, Ed., Academic Press, San Diego (2001) Vol 1, Chapter 2 (ISBN 0-12-512908-4).
Thus there is a need for a photomask material which will not degrade at temperatures necessary for CVD processes. There is a further need for a method of fabrication of disk drive read heads which uses high temperature photomasks when using high temperature processes such as ALD.